Chances of a girl catching HIV from a HIV positive male from oral sex alone is very, very, very remote. Infact, catching HIV at all isnt that easy believe it or not. Its a frail virus and can only be transmitted if conditions are perfect. For oral transmission, the girl must have cuts in her mouth, open sores, recent dental work etc. The guy must have a high viral load. So i wouldnt worry about oral sex as much, your much more likely to catch one of the more common STDs.
Provided YOU use a condom correctly and that includes for oral, then you are 97% protected from catching HIV. The remaining 3% risk comes from incorrect condom use, faulty condom or breakage. And if your giving the girl oral, then the risk to you is basically so remote any professional will tell you its nearly impossible to catch HIV from licking pussy.
So - if I said to you that you had a 97% chance of winning the lottery jackpot, what would you do? Still not play?